в Builder -ой справке
| Цитата |
basic_ifstream(const char* s,
ios_base::openmode mode= ios_base::in,
long protection= 0666);
Constructs an object of class basic_ifstream<charT,traits>, initializing the base class basic_istream with the associated file buffer, which is initialized by calling the basic_filebuf constructor basic_filebuf<charT,traits>(). The constructor then calls the open function open(s,mode,protection) in order to attach the file, whose name is pointed to by s, to the basic_ifstream object. The third argument protection holds file permissions. It does not appear in the Standard C++ description and is included as an extension. It determines the file read/write/execute permissions under UNIX. It is more limited under DOS since files are always readable and do not have special execute permission.
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А вот что в исходниках
| Код |
template <class _CharT, class _Traits>
class basic_ifstream : public basic_istream<_CharT, _Traits>
{
public: // Types
typedef _CharT char_type;
typedef typename _Traits::int_type int_type;
typedef typename _Traits::pos_type pos_type;
typedef typename _Traits::off_type off_type;
typedef _Traits traits_type;
typedef basic_ios<_CharT, _Traits> _Basic_ios;
typedef basic_istream<_CharT, _Traits> _Base;
typedef basic_filebuf<_CharT, _Traits> _Buf;
public: // Constructors, destructor.
basic_ifstream() :
basic_ios<_CharT, _Traits>(), basic_istream<_CharT, _Traits>(0), _M_buf() {
this->init(&_M_buf);
}
explicit basic_ifstream(const char* __s, ios_base::openmode __mod = ios_base::in) :
basic_ios<_CharT, _Traits>(), basic_istream<_CharT, _Traits>(0),
_M_buf() {
this->init(&_M_buf);
if (!_M_buf.open(__s, __mod | ios_base::in))
this->setstate(ios_base::failbit);
}
# ifndef _STLP_NO_EXTENSIONS
explicit basic_ifstream(int __id, ios_base::openmode __mod = ios_base::in) :
basic_ios<_CharT, _Traits>(), basic_istream<_CharT, _Traits>(0), _M_buf() {
this->init(&_M_buf);
if (!_M_buf.open(__id, __mod | ios_base::in))
this->setstate(ios_base::failbit);
}
# endif
~basic_ifstream() {}
public: // File and buffer operations.
basic_filebuf<_CharT, _Traits>* rdbuf() const
{ return __CONST_CAST(_Buf*,&_M_buf); }
bool is_open() {
return this->rdbuf()->is_open();
}
void open(const char* __s, ios_base::openmode __mod = ios_base::in) {
if (!this->rdbuf()->open(__s, __mod | ios_base::in))
this->setstate(ios_base::failbit);
}
.................
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Заметь ни в одном конструкторе нет 3-го параметра. Видимо он вообще не используется  |
, компилер ВСВ6 ругается (реализации STL разные). В хэлпе ВСВ6 написано мякго говоря мало. И потому спрашиваю, что в 3 параметре должно быть. В частности интересует константа задающая так сказать "эсклюзивный" доступ(тобишь другие приложения не могут открыть файл). 
.